I usually dont fill my tank up, cause im a broke ass college kid... but when i do - i notice that even when i get it filled (in NJ someone pumps for me) the gauge usually only shows 3/4 full or almost 7/8 filled. even when i fill it on my own outside of NJ its usually around 3/4 full. anyone else experince filling up but it only goes to 3/4 full on gauge - or know why this happens/how to fix it?

no, it doesnt go higher after i start driving and isnt on a hill or anything, affecting the sensor

 

Do you leave your car on while it's filling up? That could **** the sensor, I heard.

 

do you put that tab on the pump handle to full blast?

Try only doing the 1st click in (slow) and see if it fills up all the way.

 

^ What he said. Normally, when it clicks, I keep pumping until it spurs out a little. Normally, I get an extra gallon in.

 

I have to fill my ss and escape on the 1st click tab thing (slowest) or it will over flow my tank or click off all the time. its the best method I've found.

 

i dont leave my car on, thats how gas stations blow up.
ive tried numerous ways of filing up, slow fast - keep pulling handle but it pops right back out.
never had the gauge show 100% full.... always about 3/4

 

Ever wonder why the fuel truck fills the tanks up with it's motor on..?

 

Unless you like doing fuel pumps you should always keep a good amount of gas in your tank. It's the only thing that cools the pump.

 

is there a float in our tank that shows how high? maybe yours is whack out.

But how many miles do you usually get on a tank? better yet, after driving a while does your needle not move like the tank was full but the needle just doesnt go all the way to full. Like 3/4 a tank is maybe 60 miles for me.

 

That isn't good for your car. The gas needs that extra room to expand. The extra gas will evaporate into your vapor collection system causing it to **** up. Then the car will run like **** and have high gas emissions.

Plus it can damage the fuel gauge sensor (which is probably what the OP has).

 

yeah, there is a flotation device that is basically the gas gauge attached to the pump. Might be screwed up. Does your needle ever go past empty? Like say 1/8 or 1/4? If so it could be something with the needle. If thats the case you can confirm by seeing how many miles you get to a gallon and compare to a norm cobalt. like northvibe was saying.

 

congrats, you are filling up your charcoal/carbon canister full of fuel.

 

i can make it from WVU to my house (318 miles) on 1 tank of gas.... 31mpg highway. and the needle doesnt go past the empty O (needle isnt messed up)... idk.. it probably is the sensor.

 

I guess it would be more accurate to figure out exactly what gallon tank it is, and fill it up from empty. If it fills up to how many gallons you could hold, then there you go.

 

bring it to the dealer

 

good idea. will try when i get paid

not bringing to dealer. my warranty ended a LONG time ago.

 

I'm pretty sure it's between 12 and 12.5 gallons.

 

It sounds like your gauge is just reading off. That is the exact gas mileage I get on a full tank.

 

i can make 20 of gas last all week... orrr friday night

 

hmph really.... so i guess the needle just wont go all the way to the right, cause the last time i came home, i literally stalled out once i got in town and coasted in neutral right into the gas station and right to the pump and this was a little after the red O (empty tank) came on. thank god no traffic/stop lights!

edit; 318 / 31 = 10.6 gallons. dont we have a 12gallon tank? ergh maybe it doesnt fill all the way?

edit2; wiki says 13gallons. 3gallons would be another 1/4 tank...

 

Yeah all I could find through google was 13 gallons. The millage thing can always be off, your MPG wont always be the same for each tank. But how much were you able to get in there when you coasted into that gas station?

 

You have to keep in mind that most gas tanks don't fill to their actual capacity tho. Leaves room for vapor expansion as others have said. So a 13 gallon tank on a "fill" up only holds about 11.5 gallons if I remember correctly.

That's why the pump kicks itself off and it says on the pump "vapor recovery system" and "do not top off tank". Its there both so you don't let out obnoxious amounts of fumes and so you don't over fill ur tank and close up the extra space that's supposed to be in there.

 

With most of the pumps around here (on both my TC and 2.2) I have to turn the nozzle about 45 degrees left or right so the funnell isn't straight down in the tank otherwise it shuts off numerous times during the fill-up. On a hot day it will occasionally get to about 3/4 full and then stop and looking at the load of fuel I know I'm well short of a full tank and all I can attribute it to is back-pressure especially if the tank is exceptionally low (think of a lawn mower when you let it empty right ou on a super hot day...open the cap it's smoking).

Just a thought .

 

there is not really a lot of extra space on new tanks. there is what is called a "charcoal" or "carbon" canister which is what stores the fumes

 

Float is probably off...I've filled my Cobalt about once a week for the past 4 years, and have never had an issue. Same routine every time - I'll drive till low the first low fuel indicator (you *should* have 1.5-2 gallons left at that point), and fill the tank at next opportunity. I usually get 11 gallons, but if I've driven on low fuel for a while, I may get to 12. I never add after the auto shut off.